Virtualization of service functions is fast growing technology that allows scaling to demand of customers using, for example, cloud technology. A service function is an application that provides data storage, manipulation, presentation, communication or other capability which may be implemented using client-server or peer-to-peer architecture based on network protocols.
The delivery of end-to-end service may require various service functions. The instantiation of a set of service functions and the steering of data traffic, such as packets or frames, through the set of service functions is known as Service Function Chaining (SFC). A service function chain includes a set of service functions and constraints that can be applied to packets and/or frames and/or flows selected as a result of classification. A service function can be responsible for specific treatment of received packets. Examples of service functions include firewalls, wide area network and application acceleration, Network Address Translation (NAT), HTTP Header Enrichment functions, and TCP optimizer.
A service function is one of elements that can form the SFC and it can provide adaptation and forwarding of data to and from the Virtual Network Function (VNF) instance. Control and management of a service function can be realized via either SFC control protocol in a distributed model or via a controller in a centralized model. Virtualization of service functions decouples the service functions from the hardware devices so that the service functions can run in software. A VNF can handle specific network functions that run on one or more virtual machines (VMs) on top of the hardware networking infrastructure, such as routers, and switches. A VNF can be designed to consolidate and deliver the networking components to support a fully virtualized infrastructure including virtual servers, storage, and even other networks. Individual virtual network functions can be connected or combined together as building blocks to offer a full-scale networking communication service.